1. Field of the Invention
The present invention relates to a liquid crystal display device used for in a projection display television and more particularly to a fine or small-sized liquid crystal display device having a pixel size of about 100 .mu.m or less.
2. Description of the Related Art
In recent years, the liquid crystal display device has been used in various fields in view of using the various features such as light weight, low consumption cost of electric power, and the like. In particular, attention has been paid to a liquid crystal display device, which drives each pixel electrode through a switching element and provides a good display without crosstalk.
This type of liquid crystal device comprises an array substrate and an opposing substrate which are spaced apart from each other by a distance of about 5 .mu.m, and having a liquid crystal layer sealed between these substrates. Signal lines to which image signal are applied and scanning lines to which ON-OFF control signals (scanning signals) for switching transistors are applied are formed on the array substrate in a matrix manner. Pixel electrodes are respectively formed in the areas enclosed with the signal lines and the scanning lines, and each pixel electrode is connected to the corresponding signal line through the switching transistor. If an ON signal is applied to the scanning line, the switching transistors connected to the scanning line are turned on, and each electrical potential of the signal line is supplied to the pixel electrode formed of a transparent conductive film.
Storage electrodes extending in parallel to the scanning lines are formed on the array substrate. Each storage electrode forms a MOS capacity between a part of the pixel electrode and the storage electrode in order to suppress the variation of the pixel potential, which is caused by crosstalk between the signal lines or the scanning lines and the pixel electrode and leak current at the switching transistor.
A transparent conductive film is formed on the entire surface of the opposing substrate, and a light-shielding film is formed thereon to define the opening area of the display device.
In the above-explained liquid crystal display device, the size of each pixel is about 60 .mu.m.times.60 .mu.m. However, smaller or finer liquid crystal display devices are required, and to achieve such, it is necessary that the pixel size be further reduced.
However, the reduction of the pixel size causes various problems, and the following two major problems can be particularly explained.
One problem is that a coupling capacitance rapidly increases as the distance between the signal line and the pixel electrode is narrowed, so that crosstalk is generated between the pixel electrode and the signal line and the pixel potential is varied.
The other problem is that disorder of the orientation of a crystal liquid occurs along the signal line by a lateral electrical field generated between the signal line and the pixel electrode. Since the disorder of the orientation of the crystal liquid ranges from the signal line to 7 to 15 .mu.m, the problem becomes more serious if the pixel size is reduced.
The above problems can be solved by sufficiently widening the space between the signal line and the pixel electrode.
However, if the space between the signal line and the pixel electrode is widened in addition to the reduction of each pixel size, the aperture ratio ((area through which light can transmit)/(pixel area)) is considerably lowered, and the image on the screen becomes extremely dark.
On the other hand, in recent years, the coloring of the liquid crystal display device to be used in a view finder and a head-up display and the like has been advanced. In projection display televisions, images can be colored by using dichroic mirrors for performing color separation and three monochrome liquid crystal display devices. However, in the case of the view finder or the head-up display, since there is no space for arranging a complicated optical system, it is required that color display can be performed by a single liquid crystal display device. To achieve this object, normally, the liquid crystal display device is colored by using a color filter formed on the opposing substrate.
However, if the pixel pitch is reduced in accordance with the miniaturization of the pixel, it is difficult to correctly align the color filter on the opposing substrate with the pixels on the array substrate.